The brain mechanisms of pain-induced fighting are being analyzed in terms of sensory systems, motor components, and single unit recording from integration centers of the brain. Pain-induced fighting is analyzed in pairs of rats with deprivation of single sensory modalities and combinations of sensory deprivations. The goals are to determine which sensory modalities are critical for the behavior, and to prepare animals which use only one modality to mediate the behavior. Motor components of the behavior are being analyzed by videotape system using slow motion and stop-frame action. Single unit activity from the midbrain central gray and surrounding regions is being recorded during pain-induced fighting. Glass insulated tungsten microelectrodes are lowered by a specially designed miniature microdrive. Unit activity is amplified by a miniature DC preamplifier, on an oscilloscope, and audio monitor recorded by tape recorder, fed through an amplitude discriminator, and recorded along with the animals' behavior on videotape.